Oxygen vacancies-rich Ce_0.9Gd_0.1O_2-δ decorated Pr_0.5Ba_0.5CoO_3-δ bifunctional catalyst for efficient and long-lasting rechargeable Zn-air batteries

Rational design of bifunctional catalysts towards oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is vital for reversible Zn-air batteries. Here, we highlight the surface functionalized perovskite, oxygen vacancies-rich Ce_0.9Gd_0.1O_2-δ (GDC) decorated Pr_0.5Ba_0.5CoO_3-δ (PBC), as a novel bifunctional electrode for Zn-air batteries. Surface decoration by GDC can not only introduce the abundant electrochemically active oxygen vacancies for ORR and OER, but also improve the structure stability of perovskite against practical operation. Density functional theory calculations further reveal that O₂ and H₂O molecules readily adsorb on GDC surface rather than PBC surface. The resulting 20 wt.% GDC decorated PBC catalyst delivers a significantly higher bifunctionality than the pristine PBC. As a proof-of-concept, an assembled Zn–air battery using 20 wt.% GDC decorated PBC electrode demonstrates a considerable peak power density and a long cycling life. This study offers a facile and effective approach to design air electrode of rechargeable Zn-air batteries. © 2020 Elsevier B.V.